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totallytech

macrumors newbie
Original poster
Feb 13, 2013
5
0
Hey Guys,

I've got a 2008 aluminimum 24" imac. 3.06GHz, 4GB, 250GB. The screen started to just turn off around 2 weeks ago. Sometimes the machine would power on and work for around 1-2 hours, but sometimes only around 15 minutes.

The screen just goes black. No funny flickering, no odd pixels etc. Just off.

The superdrive is still reading etc, if I put in a disk it spins and reads, I can also hear the hard drive reading etc.

I opened the imac and checked the graphics card. Its the 512MB Nvidia 880GS.

I sent the graphics card to a company to test it and it worked directly in one of their machines for an entire day.

I've replaced the ram and the lcd screen too.

When I power up the machine I check the little diagnostic leds and it shows

LED 1 - ON
LED 2 - ON
LED 3 - ON
LED 4 - OFF

but the screen is just black.

Any ideas - I'm thinking it may be the logicboard but surely the dvd drive and hard drive wouldnt power on?
 

kpgh554

macrumors regular
Dec 29, 2011
201
1
iver england
Hey Guys,

I've got a 2008 aluminimum 24" imac. 3.06GHz, 4GB, 250GB. The screen started to just turn off around 2 weeks ago. Sometimes the machine would power on and work for around 1-2 hours, but sometimes only around 15 minutes.

The screen just goes black. No funny flickering, no odd pixels etc. Just off.

The superdrive is still reading etc, if I put in a disk it spins and reads, I can also hear the hard drive reading etc.

I opened the imac and checked the graphics card. Its the 512MB Nvidia 880GS.



I sent the graphics card to a company to test it and it worked directly in one of their machines for an entire day.

I've replaced the ram and the lcd screen too.

When I power up the machine I check the little diagnostic leds and it shows

LED 1 - ON
LED 2 - ON
LED 3 - ON
LED 4 - OFF

but the screen is just black.

Any ideas - I'm thinking it may be the logicboard but surely the dvd drive and hard drive wouldnt power on?

LED off- means video card and logic board not communicating apple recommend replace either.{you have.} but have you tested the inverter not problem. and no wires loose or pinched. other than that sound like mother board to me.
 

totallytech

macrumors newbie
Original poster
Feb 13, 2013
5
0
Hey,

I've not checked the invertor, but I have tried two complete lcd screens - the LCD's have the inverters installed so I'm guessing they are fine...

If the logicboard / mainboard has failed would the dvd drive etc still power on?

----------

I have noticed though none of the fans are coming on when I turn on the machine....
 

kpgh554

macrumors regular
Dec 29, 2011
201
1
iver england
Hey,

I've not checked the invertor, but I have tried two complete lcd screens - the LCD's have the inverters installed so I'm guessing they are fine...

If the logicboard / mainboard has failed would the dvd drive etc still power on?

----------

I have noticed though none of the fans are coming on when I turn on the machine....

I think dvd drive and hdd powered by psu and only controlled by mother board and fans run by mother board, not sure but someone else may say different.
 
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